DE3045691C2 - - Google Patents

Description

The invention relates to a method for producing a Laminate of a film and a paper fiber layer.

Films are given printability by conventional methods or writability, by either a) the surface the film oxidizes, b) convex and concave areas on the Surface of the film forms or c) a paper to a film binds. The method a, for example, with a corona discharge or by flaming and method b, for example performed with a sandblast or by etching. For method c, for example, it is "General paper Rundschau ", No. 7, 1954, pages 280 to 290, Papers with plastics in solutions or hydrous To coat dispersions or by means of heated rollers to laminate a paper sheet with a plastic film.

However, the products of methods a and b are disadvantageous because of as they are not an oily or aqueous printing ink absorb and thus a long time is required to To dry inks. In addition, the printing inks adhere bad on the slides. Products obtained by method c retain the paper's own advantages, such as printability and writability. But because these products are made from one relatively thick paper with a basis weight greater than 20 g / m² and a film bound thereto, go Transparency and smoothness inherent in the film, lost, and the products feel stiff. also the products easily swell due to shrinkage or stretching of the paper.

The object underlying the invention was therefore to a laminate of a film and a paper fiber layer to get that the good qualities of both the Film as well as the paper, and on the other hand excellent  Suppleness, transparency and tear resistance and on the other hand, good writability and printability Has.

So should the laminate as tracing paper, computer paper or recording paper suitable for printers or measuring devices and be very easy to manufacture at low cost.

The method according to the invention is characterized that on the two surfaces of the paper in each case a film is applied adhesively and that the composite of the films and the paper is separated so that on each of separated sheets the paper fiber layer remains.

In the laminate according to the invention, since the to the film bonded paper fiber layer is very thin and its basis weight Expediently only 5 to 15 g / m², preferably 5 to 8 g / m² which is difficult to achieve by conventional methods can not be lost, the transparency of the slide and will reduce the dimensional stability or a Waves of the laminate due to stretching or shrinkage prevents the paper fiber layer. Plus that feels Laminate not stiff, and the tear strength of the film remains fully intact.

In addition, there is no smearing of the printing inks or the like, and the applied inks can be dry easily. You get good printability and writability, that are inherent in the paper.

Accordingly, the laminate according to the invention is very suitable and valuable as tracing paper and can be widely used as a computer strip or as recording paper for a printout or measuring device can be used. Since the laminate after a very simple process can be made In addition, the production costs are greatly reduced, and you can easily mass-produce it.  

In the drawing mean

Figure 1 is an enlarged view of a section in the thickness direction of the laminate according to the invention.

Fig. 2 is a flowchart showing an embodiment of the method for producing a laminate according to the invention, and

Fig. 3 is an enlarged view showing the outlined in Fig. 2 by dashed lines area.

According to FIG. 1, the laminate 1 according to the invention consists of a film 2 and a paper fiber layer 3 bonded thereto. This laminate 1 is produced by the method described below. In it, the basis weight of the paper fiber layer 3 bonded to the film 2 is usually 5 to 15 g / m 2, and preferably 5 to 8 g / m 2. In the invention, the basis weight of the paper fiber layer 3 is preferably set in the above-mentioned range for the following reasons.

When the portion of a printed or written paper is observed under a microscope, it can be seen that the basis weight of the paper fiber layer required for the penetration of an ink or the like is 5 to 8 g / m². In other words, the minimum basis weight of the paper fiber layer required to impart paper properties such as printability or writability to the laminate is 5 to 8 g / m². When the basis weight of the paper fiber layer 3 is smaller than 5 g / m 2, a printing ink or the like penetrates the paper fiber layer 3 and arrives at the surface of the film, with the result that smearing of the ink may be caused or a long time for the printing Drying the ink is required.

When the basis weight of the paper fiber layer 3 is larger than 15 g / m², the laminate becomes similar to a product obtained by laminating a paper with a film, the transparency and dimensional stability inherent in the film are lost in the resulting laminate, and the laminate becomes stiff and loses its suppleness.

In the invention, the type of material from which the Film is not particularly critical. For example, can a polyvinyl chloride, polyethylene, polypropylene, polystyrene, Polyacetate, polycarbonate, polyester, polyamide, Polyimide or chlorinated rubber sheet can be used.

Any adhesive may be used to bond the film 2 to the paper fiber layer 3 , provided that the requirement that the adhesive bond strength between the film and the paper be greater than the tearable layer's tearability is met. For example, copolymers of vinyl acetate, ethylene, acrylonitrile or vinyl chloride, rubber type adhesives such as natural rubber, butyl rubber, nitrile rubber, neoprene rubber and chloroprene rubber, epoxy type adhesives, unsaturated polyester type adhesives and copolycondensed saturated polyester type adhesives can be used. These adhesives may be used singly or in the form of a mixture of two or more of them.

The process for producing the laminate shown in FIG. 1 will now be described with reference to FIGS. 2 and 3.

In Fig. 2, films are wound on rolls 4 and 5 , respectively, and a paper is wound on a roll 6 . Sheets 7 and 8 are removed from rolls 4 and 5 , and an adhesive is applied to a surface of each of sheets 7 and 8 at points A and B. The adhesive films are heated by dryers 10 and 11 to remove the solvent from the adhesive. A paper 9 is removed from the roll 6 , and the sheets 7 and 8 are dry-laminated on both surfaces of the paper 9 by means of rolls 12 and 13 to form a film-paper-foil laminate 14 .

In the invention, it is important that the adhesive applied at points A and B have such a property that the adhesive bonding strength between the paper 9 and the films 7 or 8 is greater than the tensile strength of the fiber layer of the paper 9 .

The laminate 14 is then cooled by rollers 15 and 16 and the films are separated from the paper by delamination. More specifically, if the films of the laminate 14 are peeled at any peel rate such that the angles α and β of the peel directions are equal to the centerline X of the composite, then the tearing stress is substantially at the center of the thickness of the fibrous layer of the paper 9 , with the result that the fiber layer of the paper 9 breaks substantially in the middle of its thickness and the fiber layer is divided into two parts. Thus, laminates 19 and 20 are obtained in which the thickness of the fiber layers bonded to the films 7 and 8 are substantially equal.

When the adhesive bond strength between the film and less paper than the tensile strength of the paper fiber layer is, when peeling or separating is no Tearing the paper causes, but only the Films separated from the paper, and you get no laminate.

The weight per unit area of the paper 9 delivered by the roll 6 is 15 to 30 g / m², preferably 15 to 20 g / m². A paper with a basis weight smaller than 15 g / m² can hardly be obtained according to the current papermaking methods. When a paper having a basis weight greater than 30 g / m² is used, the basis weight of the paper fiber layer of the laminate obtained at the separation is larger than 15 g / m², which is undesirable.

The type of paper used in the invention is not particularly critical to the invention, if that Basis weight is in the range of 15 to 30 g / m². For example Any of these can usually be machined Papers and Japanese papers are used. Even if a Japanese paper in which the length of the paper fibers relative is great, one can use a laminate with one Smooth surface, directly for practical use can be used. The binding of the paper the films can be either by dry lamination or Wet lamination done. The dry lamination process However, it is preferred because the adhesive is in the case of the wet lamination process penetrates into the interior of the paper.

In the embodiment shown in FIG. 2, a laminate having a paper fiber layer bonded to only one surface of a film is shown. According to the invention, however, laminates in which paper fiber layers are bonded to both surfaces of a film can be produced in a similar manner.

More specifically, in the latter case, laminates prepared in the same manner as above are wound on the rolls 4 and 5 shown in Fig. 2, respectively, so that the film layer of each laminate lies on the inside, and a paper 9 is on the inside Roll 6 wound up. In this way you get a laminate with a paper fiber layer on both sides of the film.

example

An adhesive having the composition shown below was as a coating on a surface of a biaxially stretched Polyethylene terephthalate film with a thickness of 25 microns applied, and the coated film was dried to to remove the solvent of the adhesive.

Copolycondensed saturated polyester 15 parts by weight epoxy resin 3 parts by weight isocyanate prepolymer 2 parts by weight Solvent (mixture of toluene / methyl ketone / dioxane in the ratio 7: 2: 1) 80 parts by weight

The polyester films coated with the above adhesive were dry-laminated on the front side and the back side of a Japanese paper having a basis weight of 15.6 g / m 2, a thickness of 28 μm and a density of 0.56. After cooling, the films on the front and back sides of the resulting laminate were delaminated such that both peel angles (α and β in Figs. 2 and 3) were equal to each other. The separation speed was set at 100 m / min, and by keeping the peel angles equal to each other, when the films were separated, such a stress was generated that it acted on substantially the center of the thickness of the paper fiber layer. Thus, laminates were obtained each comprising the polyester film and the paper fiber layer having a basis weight of 6.5 to 8.5 g / m 2 bonded to the film. The deviation of the thickness of the paper fiber layer was about 2.0 g / m 2, calculated as the basis weight.

The surface of the paper fiber layer of each laminate was so smooth that the surface of the paper fiber layer of the Laminate directly printed, described or for recording could be used.

Comparative example

Comparative tests were carried out with the laminate according to the invention, which was prepared according to the above example, a conventional laminate of a Japanese paper bound Film and a sandblasted film with a thickness made of 50 microns. The results obtained are in the following table.  

table

The ink adhesion, the drying time to touch, the waves, transparency and stiffness faded evaluated by the following methods:

Druckfarbenanhaftung

A letter was on a sample with an oily one Written ink or an aqueous ink, and the surface described was washed ten times with an eraser erased. The degree of reduction in the density of the written Letter was observed with the naked eye. The symbol "○" shows good ink adhesion, and the symbol "Δ" shows a fairly insufficient ink adhesion.

Drying time to touch

A letter was written on a sample, and the one described Surface was with a finger at intervals  each grated for 1 second. The time required was, so that the ink dried so far that it through Rubbing with the finger was no longer blurred, was measured.

waves

A sample was left for 10 minutes in a conditioning chamber standing at a temperature of 25 ° C and a relative Humidity of 45, 65 or 85% has been maintained, and the waves of the sample were tested. The symbol "○" indicates that no waves entered, and the symbol "×" indicates that Waves was caused.

transparency

The transparency was determined by the method JIS P 8138 and calculated according to the following formula:

Transparency (%) = 100 - (Hunter opacity value)

stiffness

Stiffness was measured using a Gurley Stiffness Tester certainly.

From the results shown in the table it is understandable that the laminate according to the invention excellent compared to the conventional laminate of a paper-bound Foil and compared to the surface-treated sandblasted film in terms of ink adhesion, of the wave, the dry season to touch, the Transparency and rigidity is.

Claims (2)

1. A process for producing a laminate of a film and a paper fiber layer, characterized in that on the two surfaces of the paper in each case a film is adhesively applied and that the composite of the films and the paper is separated so that on each of the separate films the paper fiber layer remains. 2. The method according to claim 1, characterized in that when separating the slides, the angles of the slides in question are equal to each other to the center line of the composite.